Electronic endoscope system

1. An electronic endoscope system including a scope having a solid-state image sensor provided at a distal end thereof to generate image-pixel signals, and an image-signal processing unit that produces a video signal based on the image-pixel signals, which system comprises: an alteration system that alters a peak-to-peak level of a synchronizing-signal component of said video signal; an manual setting system that manually operates said alteration system to perform the alteration of the peak-to-peak level of said synchronizing-signal component; an indicator system that indicates a degree of the alteration of the peak-to-peak level of said synchronizing-signal component during the operation of said manual setting system; and an output terminal that outputs said synchronizing-signal component having the peak-to-peak level defined by said alteration system.

2. An electronic endoscope system as set forth in claim 1 , wherein said manual setting system is provided in a housing of said image-signal processing unit so as to be accessible by a suitable manual tool.

3. An electronic endoscope system as set forth in claim 1 , wherein said alteration system comprises a voltage-controlled amplifier, an amplification factor of which is regulated in accordance with a level of a voltage signal applied thereto, and said manual setting system comprises a variable resistor that adjusts the level of said voltage signal.

4. An electronic endoscope system as set forth in claim 1 , wherein said indicator system includes an indicator lamp visually provided at a suitable location of a housing of said image-signal processing unit, and a lamp driver system that controls lighting of said indicator lamp in accordance with the degree of alteration of the peak-to-peak level of said synchronizing-signal component.

5. An electronic endoscope system as set forth in claim 4 , wherein said indicator lamp includes at least two light-emitting sources, and said driver system controls not only turn-ON and turn-OFF of said light-emitting sources but also brightness of said light-emitting sources in accordance with the degree of the alteration of the peak-to-peak level of said synchronizing-signal component.

6. An electronic endoscope system as set forth in claim 5 , wherein said respective light-emitting sources emit different monochromatic light.

7. An electronic endoscope system as set forth in claim 4 , wherein said lamp driver system includes an ON/OFF switch element that controls supply of electrical power from said lamp driver system to said indicator lamp, and a timer system that turns OFF said ON/OFF switch element after a predetermined time is elapsed from a time at which said ON/OFF switch is turned ON.

8. An electronic endoscope system as set forth in claim 1 , wherein said alteration system comprises a voltage-controlled amplifier, an amplification factor of which is regulated in accordance with a level of a voltage signal applied thereto, and said manual setting system comprises a variable resistor that adjusts the level of said voltage signal, said manual setting system being provided in a housing of said image-signal processing unit so as to be accessible by a suitable manual tool.

9. An electronic endoscope system as set forth in claim 8 , wherein said indicator system includes an indicator lamp visually provided at a suitable location of the housing of said image-signal processing unit, and a lamp driver system that controls lighting of said indicator lamp in accordance with the degree of alteration of the peak-to-peak level of said synchronizing-signal component.

10. An electronic endoscope system as set forth in claim 9 , wherein said indicator lamp includes at least two light-emitting sources, and said driver system controls not only turn-ON and turn-OFF of said light-emitting sources but also brightness of said light-emitting sources in accordance with the degree of alteration of the peak-to-peak level of said synchronizing-signal component.

11. An electronic endoscope system as set forth in claim 10 , wherein said respective light-emitting sources emit different monochromatic light.

12. An electronic endoscope system as set forth in claim 9 , wherein said lamp driver system includes a tool-detection system that detects whether access to said manual setting system by said manual tool is made, and said lamp driver system is allowed to feed electric power to said indicator lamp only when the access to said manual setting system by said manual tool is detected by said tool-detection system.

13. An electronic endoscope system as set forth in claim 12 , wherein said lamp driver system further includes an ON/OFF switch element that controls the supply of the electrical power from said lamp driver system to said indicator lamp, and said ON/OFF switch is turned ON only when the access to said manual setting system by said manual tool is detected by said tool-detection system.

14. An electronic endoscope system as set forth in claim 1 , wherein said manual setting system includes a portion which is manually operated by a suitable manual tool, and which is arranged such that the manual tool is operable without interfering with a signal cable extending from said output terminal.